JP4487353B2 - Polishing apparatus and polishing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing apparatus and a polishing method.
[0002]
[Prior art]
As semiconductor devices are highly integrated and multi-layered, the flattening of various interlayer insulating films or other films has become important in the manufacturing process of semiconductor devices.
Various means have been proposed as a technique for planarization. Recently, a CMP (Chemical Mechanical Polishing) method using a mirror polishing technique of a silicon wafer has been attracting attention and has been used. A method of flattening has been developed.
An example of a polishing apparatus using a conventional CMP method is shown in FIG.
A polishing apparatus 301 shown in FIG. 17 includes a spindle spindle 303 that rotates a polishing tool 302 and a table 304 that holds a wafer W.
The table 304 is rotatably mounted on a slider 306 provided so as to be movable in the X-axis direction along the rail 305. For example, the table 304 is rotationally driven by a rotational driving means including a motor, a pulley, a belt, and the like. Is done.
The main spindle 303 is held movably in the Z-axis direction, and is positioned at a target position in the Z-axis direction by a drive mechanism (not shown).
In the polishing apparatus 301 having the above-described configuration, first, the wafer W is rotated at a predetermined number of revolutions, and, for example, an abrasive in which abrasive grains such as silicon oxide are mixed with a liquid such as an aqueous solution of potassium hydroxide on the wafer W. The slurry is supplied onto the wafer W from a slurry supply device (not shown).
Next, the polishing tool 302 is rotated at a predetermined number of revolutions, and the wafer W and the polishing tool 302 are in the X-axis and Z-axis directions so that the outer peripheral end portion of the polishing tool 302 overlaps and contacts the outer peripheral end portion of the wafer W. Is positioned.
The polishing tool 302 is positioned in the Z-axis direction so as to have a predetermined cutting amount with respect to the wafer W, whereby a predetermined processing pressure is generated between the polishing tool 302 and the wafer W. In this state, the wafer W is moved in the X-axis direction at a predetermined speed pattern, and the wafer W is polished while the polishing tool 302 is in contact with the wafer W, so that the wafer W is flattened.
[0003]
[Problems to be solved by the invention]
By the way, in the polishing apparatus 301 having the above-described configuration, the polishing surface 302a of the polishing tool 302 is parallel to the holding surface of the rotary table 304, and the polishing tool 302 is polished according to the relative movement of the polishing tool 302 with respect to the wafer W in the X-axis direction. The overlapping region of the surface 302a and the surface to be polished of the wafer W is in full contact. For this reason, the area of the effective working area of the polishing surface 302a of the polishing tool 302 with respect to the surface to be polished of the wafer W is an area where the polishing surface 302a of the polishing tool 302 and the surface to be polished of the wafer W overlap, and this area is compared. Also, it changes according to the relative movement of the polishing tool 302 in the X-axis direction.
If the area of the effective working area of the polishing surface 302a of the polishing tool 302 with respect to the surface to be polished of the wafer W is large, the amount of polishing in the effective working area is not uniform due to unevenness or the like existing on the surface to be polished of the wafer W. If the area of the effective working region changes, the polishing rate, which is the polishing amount per unit time, changes, and it is difficult to uniformly polish the surface to be polished of the wafer W. Further, if the polishing surface 302a of the polishing tool 302 and the surface to be polished of the wafer W are parallel, the slurry is difficult to enter between the polishing surface 302a of the polishing tool 302 and the surface to be polished of the wafer W. The polishing amount may not be stable.
[0004]
For this reason, conventionally, for example, as shown in FIG. 18A, the rotation axis K1 of the polishing tool 302 is inclined at an inclination angle α toward the advancing direction of the polishing tool 302.
Here, FIG. 19 shows the pressure distribution generated between the polishing surface 302a of the polishing tool 302 and the surface to be polished of the wafer W when the rotation axis K1 of the polishing tool 302 is inclined in the traveling direction of the polishing tool 302. FIG. FIG. 19 shows a virtual pressure distribution when the surface to be polished of the wafer W is polished by rotating only the polishing tool 302 without rotating the wafer W.
As shown in FIG. 19, the pressure distribution generated between the polishing surface 302a of the polishing tool 302 and the surface to be polished of the wafer W becomes a substantially crescent-shaped region PR. A region PH having a relatively high pressure and a PL having a relatively low pressure are generated. The region PH having a relatively high pressure has a substantially symmetrical shape with respect to the X axis, and this region PH is a region that effectively acts on the surface to be polished of the wafer W. The area PH is sufficiently narrower than the overlapping area of the wafer W and the polishing surface 302a of the polishing tool 302, and the area PH is substantially constant even if the polishing tool 302 is relatively moved in the X-axis direction. It becomes. For this reason, the polishing amount in the effective working region can be made uniform, and the polishing rate can be made constant.
[0005]
However, the polishing tool 302 is an elastic body made of, for example, a disk-like member and made of a resin such as foamed polyurethane, for example, and as shown in FIG. Pressed against. For this reason, the polishing tool 302 pressed against the wafer W is elastically deformed.
In addition, when the polishing surface 302a of the polishing tool 302 is inclined at an inclination angle α with respect to the surface of the wafer W, when the polishing surface 302a of the polishing tool 302 rides on the wafer W, the rising region 190 and the relief shown in FIG. Each of the areas 191 is deformed, for example, as shown in FIG. 20A, the polishing surface 302a of the polishing tool 302 rides on the surface of the wafer W from the outer peripheral edge EG of the wafer W, so that the polishing surface 302a of the polishing tool 302 is elastically deformed. Then, the polishing surface 302a just before riding on the surface of the wafer W located in the vicinity of the outer peripheral end portion EG protrudes downward from the surface of the wafer W. In the escape area 191, the polishing surface 302a of the polishing tool 302 passes through the outer peripheral edge EG from the surface of the wafer W and leaves as shown in FIG. Is away from the outer peripheral edge EG of the wafer W, and the deformation is restored while the stress is relaxed.
[0006]
When the polishing surface 302a of the polishing tool 302 is elastically deformed, the portion of the polishing surface 302a that protrudes downward with respect to the surface of the wafer W comes into strong contact with the outer peripheral edge EG of the wafer W, and most of the processing energy is the polishing surface 302a. The protruding portion is spent on the operation of riding on the outer peripheral edge EG of the wafer W, and damage DM is given to the outer peripheral edge of the wafer W as shown in FIG.
When damage to the outer peripheral edge EG of the wafer W due to the protruding portion of the polishing surface 302a is accumulated, the wafer W is rotated. For example, as shown in FIG. As a result, the excessively polished portion 402 is excessively polished. If the excessive polishing portion 402 is formed, there is a disadvantage that the number of semiconductor chips formed on one wafer W is reduced and the yield is lowered.
In addition, since the processing energy is consumed for excessive polishing of the outer peripheral edge EG of the wafer W, the polishing rate, which is the polishing removal amount on the surface of the wafer W per unit time, is reduced, and the number of wafers W processed per unit time is reduced. And productivity is reduced.
[0007]
Further, in the region where the polishing surface 302a of the polishing tool 302 rides on the outer peripheral edge EG of the wafer W, the slurry is difficult to enter between the polishing surface 302a and the surface of the wafer W, and the polishing surface 302a and the surface of the wafer W Since the slurry supplied between them is insufficient, the polishing rate is lowered. In order to make up for the shortage of the slurry, a large amount of high-cost slurry must be supplied, resulting in a decrease in productivity.
Further, in the region where the polishing surface 302a of the polishing tool 302 rides on the outer peripheral edge EG of the wafer W, the damage to the polishing surface 302a is also large, and the quality of the polishing surface 302a is likely to deteriorate rapidly, and therefore the processing conditions vary. Is likely to occur. In order to prevent fluctuations in the processing conditions, it is necessary to condition the polishing surface 302a by means such as dressing. If the frequency of conditioning increases in order to make the state of the polishing surface 302a appropriate, the productivity of the polishing apparatus decreases.
[0008]
The present invention has been made in view of the above-described conventional problems, and can suppress excessive polishing of the outer peripheral end of the surface to be polished due to elastic deformation of the polishing tool, and An object of the present invention is to provide a polishing apparatus and a polishing method capable of stabilizing the polishing rate.
[0009]
  According to the present invention, the rotating shaft of the rotating member is held by the rotating member.WhenOrthogonalA polishing tool made of an elastic body having a polishing surface along a plane.According to the rotation of the rotating memberRotate and saidAbrasive toolA flat surface parallel to the holding surface of the holding table by pressing the polishing surface and the polishing tool relative to the polishing surface of the target object held on the holding table with a predetermined processing pressure. Relative alongInMove and saidOf the object to be polishedA polishing method for polishing a surface to be polished,
  The polishing toolOf the rotating member fixedThe polishing tool with respect to the direction perpendicular to the holding surface of the holding tableSaidRelative to holding tableNaDirection of movementInFirst angle toward the direction of travelOnlyTilt,And,AboveAbrasive toolThe polished surface is the aboveOf the object to be polishedIn the region that rides on the outer peripheral edge of the surface to be polishedThe elastic body provided in the polishing toolIn order to reduce elastic deformation of the polishing surface,Of rotating partsThe rotation axis is orthogonal to the direction of travelDirectionAlong the plane,Abrasive toolTo the outer edge of the surface to be polishedOf the polishing toolIn the area where the polished surface is mountedOf the object to be polishedThe height relative to the surface to be polished isAbrasive toolPolished surfaceButAboveOf the object to be polishedIn the area that escapes from the outer edge of the surface to be polishedOf the object to be polishedSecond angle in a direction higher than the height relative to the surface to be polishedOnlySlopeLet me
  The surface to be polished of the object to be polished is polished by the polishing surface of the polishing tool.
  A polishing method is provided.
[0010]
  Preferably, a polishing tool having a diameter substantially equal to the diameter of the surface to be polished of the object to be polished is used as the polishing tool, and the polishing surface of the polishing tool located outside the surface to be polished of the object to be polished The outer peripheral end of the polishing object is positioned at the outer peripheral end of the surface to be polished, and the polishing tool is moved relatively in the direction in which the overlapping area of the polishing surface and the surface to be polished increases. The surface to be polished is polished, and the polishing process is stopped at a position where the outer peripheral end of the polishing surface of the polishing tool reaches the outer peripheral end of the surface to be polished of the object to be polished.
[0011]
  Preferably, polishing is performed using a polishing tool having an annular polishing surface as the polishing tool.
[0012]
  Preferably, the polishing tool that rotates according to the rotation of the front rotating member in a state in which the rotating shaft of the rotating member is inclined at the first angle and the second angle is corrected to be parallel to the holding surface of the holding table. A polishing tool is used that has a polishing surface that is faced by being moved relatively along the correction surface of the tool.
[0013]
  Preferably, the first angle is larger than the second angle.
[0014]
  Preferably, the polishing is performed while rotating the holding table and rotating the object to be polished.
  Alternatively, preferably, the polishing is performed with the object to be polished and the polishing tool rotating in opposite directions.
[0015]
  Preferably, the polishing is performed with an abrasive interposed between the polishing surface of the polishing tool and the surface to be polished of the object to be polished.
  Further preferably, an outer peripheral end of the polishing surface of the polishing tool located outside the surface to be polished of the object to be polished is positioned at an outer peripheral end of the surface to be polished of the object to be polished, and When polishing by moving in an increasing direction of the overlapping area of the polishing surface and the surface to be polished of the object to be polished, at least the outer peripheral end of the surface to be polished of the object to be polished of the polishing surface of the polishing tool The second angle is inclined to a position at which elastic deformation of the polished surface due to riding does not occur.
  Preferably, when the polishing tool reaches a position where elastic deformation of the polishing surface due to running of the outer peripheral end of the polishing surface of the polishing surface of the polishing tool does not occur, the rotating shaft of the rotating member is held by the holding member. Be perpendicular to the table holding surface.
[0016]
  Also according to the invention,A rotating member;A holding table for holding an object to be polished;Held by the rotating member,Of the rotating memberAxis of rotationWhenAlong an orthogonal plane,Elastic bodyPolishing tool with polishing surfaceVertical axis moving means that moves the rotating member up and down in the vertical direction to separate or press the polishing surface of the polishing tool against the surface to be polished held by the holding table; and horizontal direction In the horizontal direction, the holding table is moved relative to the polishing tool and the surface to be polished of the object to be polished held on the holding table is brought into contact with or separated from the polishing surface of the polishing tool. A moving means and at least three locations on the outer periphery of the rotating member, and the rotating shaft of the rotating member is inclined in two directions orthogonal to each other in the horizontal direction;Rotation axis tilting means,
  By adjusting the rotating shaft tilting means provided at at least three places on the outer periphery of the rotating member, the horizontal moving meansThe polishing tool andSaidIn the direction of travel when bringing the holding table closer,Rotating memberThe rotation axis of the holding table is inclined by a first angle with respect to a direction perpendicular to the holding surface of the holding table,And,AboveVertical axis moving meansandMoved by the movement of the horizontal movement means,AboveAbrasive toolThe polished surface is the aboveOf the object to be polishedIn the area that rides on the outer peripheral edge of the surface to be polishedThe elastic body provided in the polishing toolIn order to reduce elastic deformation of the polishing surface,Of rotating partsThe rotation axis is orthogonal to the traveling directionIn directionAboveOf the object to be polishedTo the outer edge of the surface to be polishedOf the polishing toolIn the area where the polished surface is mountedSaidThe height relative to the surface to be polished isAbrasive toolPolished surfaceButIn the area that escapes from the outer peripheral edge of the surface to be polishedSaidThan the height relative to the surface to be polishedIncreaseSecond angleOnlyTilt,
  With the rotating shaft of the rotating member inclined by the first angle and the second angle, the polishing tool is pressed against the object to be polished by the vertical axis direction moving means to apply a processing pressure to the object to be polished. While being added to the object, the polishing surface of the object to be polished and the polishing surface of the polishing tool are brought into rotational contact according to the rotation of the rotating member, and the object to be polished is polished by the horizontal movement means. Polishing the surface to be polished of the object to be polished by relatively moving the surface and the polishing surface of the polishing tool,
  A polishing apparatus is provided.
  Preferably, the polishing tool has an annular polishing surface.
  Preferably, the polishing surface of the polishing tool relatively moves the rotating polishing tool with the rotation axis of the rotating member inclined in each direction along the correction surface of the correction tool parallel to the holding table. Facing process.
  Preferably, the polishing apparatus further includes a rotating unit that rotates the holding table.
  Preferably, the polishing apparatus further includes an abrasive supply means for supplying an abrasive interposed between the polishing surface and the surface to be polished.
[0017]
In the present invention, since the polishing tool is tilted in a direction that reduces the elastic deformation of the polishing surface in a region where the polishing surface rides on the outer peripheral end of the polishing target surface of the object to be polished, Damage to the outer peripheral end of the surface to be polished is suppressed by elastic deformation caused by running on the outer peripheral end of the surface to be polished, and concentration of processing energy on the outer peripheral end of the surface to be polished is suppressed. As a result, a decrease in the polishing rate, which is the polishing removal amount of the polishing surface of the object to be polished per unit time, is suppressed.
In addition, by inclining the polishing surface with respect to the surface to be polished, the height of the polishing surface in the riding region relative to the surface to be polished becomes relatively high, and the abrasive is interposed between the polishing surface and the surface to be polished. When the surface is supplied, the abrasive easily enters the rotating direction of the polishing surface between the polishing surface and the polishing surface in the riding area, and a sufficient amount of polishing is performed between the polishing surface and the polishing surface. The agent is supplied stably.
[0018]
Furthermore, the effective contact area between the polishing surface and the surface to be polished is inclined by a predetermined angle toward the direction of travel of the polishing tool with respect to the direction perpendicular to the holding surface of the holding table. Is narrowed. Thereby, the distribution of the polishing amount on the surface to be polished within the contact area is suppressed from being non-uniform, and the variation in the polishing amount within the surface to be polished is suppressed. On the other hand, when the rotation axis of the polishing tool is inclined at a predetermined angle toward the direction of movement of the polishing tool with respect to the direction perpendicular to the holding surface of the holding table, the front portion of the polishing surface in the direction of movement of the polishing tool is inclined. In the present invention, the rotation axis of the polishing tool is moved up to the polishing surface. Since the region is inclined in a direction that reduces elastic deformation, damage to the outer peripheral end of the surface to be polished can be suppressed.
[0019]
Further, in the present invention, the polishing surface is obtained by performing polishing with a polishing tool inclined at substantially the same angle as the inclination angle of the direction of travel of the polishing tool with respect to a plane perpendicular to the rotation axis. It becomes a curved surface, the effective contact area between the polished surface and the surface to be polished is further narrowed, and the height of the polished surface with respect to the surface to be polished in the region where the polishing surface rides on the surface to be polished is increased, and the elasticity of the polishing surface is increased. The amount of deformation is further reduced, and damage to the outer peripheral edge of the polished surface due to elastic deformation of the polished surface can be further suppressed.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First embodiment
FIG. 1 is a diagram showing a configuration of a polishing apparatus according to the first embodiment of the present invention.
A polishing apparatus 1 shown in FIG. 1 includes a polishing tool 8, a spindle spindle 21 that rotates and holds the polishing tool 8, a Z-axis moving mechanism 11 that moves and positions the spindle spindle 21 in the Z-axis direction, and a wafer W that holds and rotates. A rotary table 41 to be moved, and an X-axis moving mechanism 51 for moving the rotary table 41 in the X-axis direction.
[0021]
The main spindle 21 holds the polishing tool 8 and rotates the polishing tool 8 about the rotation axis K1. The main spindle 21 includes a main shaft 23, a hydrostatic bearing that rotatably holds the main shaft 23, and a servo motor that rotates the main shaft 22. The spindle spindle 21 is held by a spindle holder 20. The spindle holder 20 is held movably along the Z-axis direction by a guide (not shown) with respect to the column 3.
Further, a slurry / pure water supply nozzle 81 for supplying slurry and pure water as an abrasive onto the wafer W is provided at a predetermined position on the outer periphery of the main spindle 21.
[0022]
The Z-axis moving mechanism 11 is provided along a Z-axis direction (vertical direction) on a portal column 3 standing on the base 2 and holds a spindle spindle 21 so as to be movable in the Z-axis direction. Yes. The Z-axis moving mechanism 11 holds the polishing surface 8a of the polishing tool 8 in a direction facing the surface to be polished of the wafer W, and moves to determine the relative position of the polishing surface 8a in the facing direction with respect to the surface to be polished of the wafer W. Functions as positioning means.
Specifically, the Z-axis moving mechanism 11 includes a servo motor 12 fixed to the column 3, a screw shaft 13 formed with a screw connected to the servo motor 12, and a screw portion screwed with the screw shaft 13. And a Z-axis slider 14 formed and connected to the spindle holder 20.
By rotating and driving the servo motor 12, the Z-axis slider 14 rises or falls along the Z-axis direction, and the spindle holder 20 connected to the Z-axis slider 14 rises or falls along the Z-axis direction. Thereby, the polishing tool 8 can be positioned in the Z-axis direction by controlling the rotation amount of the servo motor 12.
[0023]
The turntable 41 includes a holding surface 41a provided in parallel to the horizontal direction for holding a wafer W as an object to be polished. The wafer W is chucked on the holding surface 41a by, for example, chucking means such as vacuum suction. King. Further, the rotary table 41 includes driving means such as a motor, and rotates the wafer W. The rotary table 41 corresponds to a specific example of the holding table of the present invention. A recovery pan 82 for recovering the slurry supplied from the slurry / pure water nozzle 81 onto the wafer W is provided around the turntable 41.
[0024]
The X-axis moving mechanism 51 includes a servo motor 55, a screw shaft 54 formed with a screw connected to the servo motor 55, an X-axis slider 53 formed with a screw portion that is screwed to the screw shaft 54, and an X-axis An X-axis table 52 connected to the slider 53 and held movably by a guide (not shown) in the X-axis direction is provided with the rotary table 41 described above.
The X-axis moving mechanism 51 holds the rotary table 41, and functions as a relative moving means of the present invention that relatively moves the polishing tool 8 and the wafer W along the holding surface 41a of the rotary table 41.
That is, by rotating the servo motor 55, the X-axis slider 53 moves in any direction in the X-axis direction, and the X-axis table 52 also moves in any direction in the X-axis direction. Since the holding surface 41 a moves in any direction in the X-axis direction along the horizontal plane, the wafer W and the polishing tool 8 move relatively along the holding surface 41 a of the turntable 41.
[0025]
The polishing tool 8 is a cylindrical member made of an elastic body that is fixed to the lower end surface of the main shaft 22 and elastically deforms when pressed against the wafer W. As a forming material of the polishing tool 8, for example, a resin such as foaming polyurethane, for example, cerium oxide (CeO) is used.₂) And fixed abrasive grains made of a soft binder can be used. As the soft binder, for example, melamine resin, urethane resin, or phenol resin can be used.
The polishing tool 8 has an annular end surface parallel to a plane perpendicular to the rotation axis K1 on the lower end surface of the cylindrical member, and this becomes a polishing surface 8a for processing the surface to be polished of the wafer W.
As the polishing tool 8, when a wafer having a diameter of 8 inches is polished, for example, a tool having a size of diameter 200 × width 20 × thickness 20 (mm) can be used. That is, the diameter of the wafer W and the outer diameter of the polishing tool 8 are substantially the same.
[0026]
Tilting mechanism of rotation axis K1
2 is provided between the spindle spindle 21 and the spindle holder 20 of the polishing apparatus 1 configured as described above, and the axis of rotation K1 of the spindle spindle 21 (polishing tool 8) is an axis perpendicular to the holding surface 41a of the rotary table 41. It is a figure for demonstrating the rotating shaft inclination mechanism which adjusts the inclination amount with respect to K2.
In FIG. 2, a flange portion 24 is formed on the outer periphery of the main spindle 21. The insertion shaft portion 27 on the upper side of the flange portion 24 of the main spindle 21 is a parallel portion at a position close to the flange portion 24 and has a tapered surface that tapers upward. The fitting hole 20b of the spindle holder 20 is inserted into the fitting.
The rotary shaft tilt mechanism 61 is provided between the upper end surface 24 a of the flange portion 24 formed on the outer periphery of the main spindle 21 and the lower end surface 20 a of the spindle holder 20. The rotating shaft tilting mechanism 61 is provided at, for example, three locations located at equal intervals in the circumferential direction of the flange portion 24.
Note that the upper end surface 24a of the flange portion 24 is a surface parallel to a plane perpendicular to the rotation axis K1 of the main spindle 21 (polishing tool 8).
[0027]
Through holes for inserting the fixing bolts 65 are formed at the installation positions of the rotary shaft tilting mechanism 61 of the flange portion 24 of the main spindle 21, and these are formed on the lower end surface 20 a of the spindle holder 20. A screw hole into which the fixing bolt 65 is screwed is formed at a position corresponding to the through hole of the main shaft spindle 21, and the flange portion 24 of the spindle spindle 21 and the lower end surface 20 a of the spindle holder 20 sandwich the rotary shaft tilt mechanism 61 therebetween. It is fixed with fixing bolts 65 sandwiched therebetween.
[0028]
As shown in FIG. 3, the rotary shaft tilt mechanism 61 includes two tilt adjustment blocks 62 and 63.
The inclination adjusting block 62 has an L-shaped cross section, and a surface 62a that contacts the lower end surface 20a of the spindle holder 20 serves as a reference surface, and is a surface opposite to the reference surface 62a. 62b is an inclined surface that is inclined with respect to the reference surface 62a.
As shown in FIG. 4, an insertion hole 62 c into which the fixing bolt 65 is inserted is formed in the reference surface 62 a of the inclination adjustment block 62.
Further, a screw hole 62e into which the tension bolt 67 is screwed and two through holes 66 into which the fixing bolts 66 are inserted on both sides of the screw hole 62e are formed in the central portion on the side surface side of the inclination adjusting block 62. Is formed.
[0029]
The inclination adjusting block 63 has an L-shaped cross section, and the surface that contacts the upper end surface 24a of the flange portion 24 of the main spindle 21 is a reference surface, and is opposite to the reference surface 63a. The side surface 63b is an inclined surface that is inclined with respect to the reference surface 63a. The inclined surface 63b is in contact with the inclined surface 62b of the inclination adjusting block 62, and is inclined at the same angle and in the opposite direction.
Further, as shown in FIG. 5, an insertion hole 63 c into which the fixing bolt 65 is inserted is formed in the reference surface 63 a of the inclination adjustment block 63.
Further, two screw holes 63 d into which the fixing bolts 66 are screwed are formed at positions corresponding to the two through holes 66 of the inclination adjustment block 62 on the side surface side of the inclination adjustment block 63.
[0030]
In a state where the inclined surface 62b of the inclination adjusting block 62 and the inclined surface 63b of the inclination adjusting block 63 are in contact with each other, the reference surface 62a of the inclination adjusting block 62 and the reference surface 63a of the inclination adjusting block 63 are parallel to each other. The relationship between the reference surface 62a of the inclination adjustment block 62 and the reference surface 63a of the inclination adjustment block 63 is determined by the relative positional relationship between the inclination surface 62b of the inclination adjustment block 62 and the inclination surface 63b of the inclination adjustment block 63. The distance TH changes.
Therefore, the distance TH can be adjusted by adjusting the relative position between the inclined surface 62b of the inclination adjusting block 62 and the inclined surface 63b of the inclination adjusting block 63, and the upper end surface 24a of the flange portion 24 of the spindle spindle 21 and the spindle can be adjusted. The distance with the lower end surface 20a of the holder 20 can be adjusted.
[0031]
That is, the inclination adjusting blocks 62 and 63 are installed at three positions between the upper end surface 24a of the flange portion 24 of the spindle 21 and the lower end surface 20a of the spindle holder 20, and the distance between the respective reference surfaces 62a and 63a. By adjusting TH, the inclination angle of the rotation axis K1 of the spindle spindle 21 (polishing tool 8) with respect to the axis K2 perpendicular to the holding surface 41a of the rotary table 41 can be arbitrarily adjusted, and in any direction Can be tilted.
To adjust the tilt angle of the rotation axis K1 of the spindle spindle 21 (polishing tool 8), first, the fixing bolt 65 for fixing the spindle spindle 21 and the spindle holder 20 is loosened, and the tension bolt 67 is directed in either direction. When turned, the tip of the tension bolt 67 contacts the side surface 63e of the inclination adjustment block 63, whereby the relative position between the inclination adjustment blocks 62, 63 can be determined, and the inclination adjustment block is determined according to this relative position. The distance TH between the reference surfaces 62a and 63a of 62 and 63 can be changed. By appropriately adjusting the distance TH between the reference surfaces 62a and 63a of the respective inclination adjustment blocks 62 and 63, the inclination direction and the inclination amount of the rotation axis K1 of the spindle spindle 21 (polishing tool 8) are adjusted.
When the distance TH between the reference surfaces 62a and 63a of the inclination adjusting blocks 62 and 63 is adjusted to a desired value, the fixing bolt 66 is tightened, the relative position between the inclination adjusting blocks 62 and 63 is fixed, and the fixing bolt is further fixed. By tightening 65, the adjustment of the inclination direction and the inclination amount of the rotation axis K1 of the spindle spindle 21 (polishing tool 8) is completed.
[0032]
Next, the polishing method of the present invention using the polishing apparatus 1 having the above configuration will be described.
Inclination of rotation axis (angle α)
First, the rotating shaft tilt mechanism 61 of the polishing apparatus 1 is adjusted so that the rotating shaft K1 of the polishing tool 8 is directed in the traveling direction of the polishing tool 8 with respect to the direction perpendicular to the plane parallel to the holding surface 41a of the rotary table 41. And tilt at a predetermined angle.
Specifically, as shown in FIG. 6, the rotation axis K1 of the polishing tool 8 is set so that the polishing tool 8 has an axis O perpendicular to a plane (XY plane) parallel to the holding surface 41a of the rotary table 41. It is inclined at an angle α toward the direction of travel D relative to the wafer W (direction of progress of polishing).
The inclination angle α of the rotation axis K1 of the polishing tool 8 is, for example, Z at the front and rear ends of the polishing surface 8a of the polishing tool 8 shown in FIG. The height difference Hα in the axial direction is set to a value of about 15 to 50 μm. That is, the inclination angle is about 15 to 50 μm with respect to the length of 8 inches.
[0033]
Inclination of rotation axis (angle β)
Further, the polishing surface 8a is elastically deformed in a region where the polishing surface 8a rides on the outer peripheral end of the surface to be polished of the wafer W with respect to the direction perpendicular to the rotary table holding surface 41a with respect to the rotation axis K1 of the polishing tool 8. Tilt in the direction to reduce.
Although the inclination of the direction for reducing the elastic deformation is not limited to one direction, preferably, the rotation axis K1 of the polishing tool 8 is set relative to the wafer W of the polishing tool 8 as shown in FIG. It is inclined at an angle β from the axis O along a plane perpendicular to the traveling direction D (Y-Z plane). 7A shows the relationship between the polishing tool 8 and the wafer W as viewed from the traveling direction D of the polishing tool 8, and FIG. 7B shows the polishing tool 8 and the wafer W as viewed from the Z-axis direction. Shows the relationship.
The direction of the inclination of the rotation axis K1 of the polishing tool 8 is such that the polishing tool 8 rides on the outer peripheral end of the wafer W 90 and the polishing tool 8 escapes from the outer peripheral end of the wafer W as shown in FIG. The height of the polishing surface 8a of the polishing tool 8 in the riding area 90 relative to the surface of the wafer W is higher than that of the escape area 91.
[0034]
The inclination angle β of the rotation axis K1 of the polishing tool 8 is such that the height difference Hβ in the Z-axis direction of the front and rear ends of the polishing surface 8a of the polishing tool 8 shown in FIG. 8 is about 15 to 30 μm, for example. Set to That is, the inclination angle is about 15 to 30 μm with respect to the length of 8 inches. Further, as will be described later, the inclination angle α of the rotation axis K1 of the polishing tool 8 is preferably set to a value larger than the inclination angle β.
[0035]
Next, in the polishing apparatus 1 in a state where the rotation axis K1 is inclined in two different directions at the inclination angles α and β, the back surface of the wafer W is fixed on the holding surface 41a of the rotary table 41, and the rotary table 41 and the polishing tool 8 are fixed. Make it rotate.
As shown in FIG. 8, the rotation direction R1 of the polishing tool 8 and the rotation direction R2 of the wafer W are opposite to each other.
[0036]
Further, as shown in FIG. 8, a predetermined amount of slurry SL is discharged from the slurry / pure water supply nozzle 81 onto the wafer W. The slurry SL is always replenished by a necessary amount even during polishing. The slurry is not particularly limited. For example, a slurry of silica-based fumed silica and high-purity ceria suspended in an aqueous solution based on potassium hydroxide for an oxide film, or alumina for a wiring metal is polished. What mixed the solvent which has oxidizing power with the processing fluid used as the abrasive grain, etc. can be used.
[0037]
Next, the polishing tool 8 is lowered in the Z-axis direction, and the outer peripheral end portion of the polishing surface 8a of the polishing tool 8 located outside the wafer W is positioned at the outer peripheral end portion as shown in FIG. The processing start point P1 at the outer peripheral edge and the outer peripheral edge of the polishing tool 8 are overlapped. In this state, the rotation centers of the polishing tool 8 and the wafer W are located on the same straight line along the X axis.
[0038]
Next, the polishing tool 8 is pressed against the wafer W to apply a processing pressure F in a direction perpendicular to the surface to be polished of the wafer W, and the wafer W and the polishing surface of the polishing tool 8 are brought into rotational contact.
From this state, the X-axis table 52 is driven to move the wafer W from the processing start point P1 in the direction of arrow C in which the overlapping area of the wafer W and the polishing tool 8 relatively increases in a predetermined speed pattern. . Thereby, the polishing tool 8 relatively moves in the radial direction of the wafer W.
Note that when the polishing tool 8 is moved relative to the wafer W after the polishing surface 8a of the polishing tool 8 is brought into contact with the processing start point P1 of the wafer W at the start of polishing, the processing pressure F is determined by polishing. When the polishing tool 8 reaches a predetermined position with respect to the wafer W, the polishing pressure is set to a constant value and polishing is performed.
The area of the crescent-shaped region described later gradually increases from the processing start point P1 as the processing pressure F increases, and after the polishing tool 8 reaches a predetermined position with respect to the wafer W, the crescent-shaped region is increased. The area of the region is a substantially constant area. Thereby, the uniformity of the polishing amount by the polishing tool 8 is obtained. Further, the velocity pattern in the X-axis direction of the polishing tool 8 is adjusted in advance so that the polishing amount in the wafer W plane is uniform.
[0039]
FIG. 9A is a view showing an example of a pressure distribution generated between the polishing surface 8a of the polishing tool 8 and the surface to be polished of the wafer W, and FIG. It is sectional drawing of the -A line direction. FIG. 9A shows a virtual pressure distribution when polishing is performed by the polishing tool 8 without rotating the wafer W.
As described with reference to FIG. 6, the rotation axis K1 of the polishing tool 8 is inclined at an angle α with respect to the axis O in the traveling direction D relative to the wafer W of the polishing tool 8. For this reason, as shown in FIG. 9A, the pressure distribution generated between the polishing surface 8a of the polishing tool 8 and the surface to be polished of the wafer W is basically a substantially crescent-shaped region PR. .
[0040]
In the crescent-shaped region PR, a region PH having a relatively high pressure and a PL having a relatively low pressure are generated. The region PH having a relatively high pressure is a region that effectively acts on the surface to be polished of the wafer W. The region PH is sufficiently narrower than the overlapping area of the wafer W and the polishing surface 8a of the polishing tool 8, and the area PH of the region PH is substantially constant even if the polishing tool 8 moves relative to the traveling direction D. It becomes. For this reason, the polishing amount in the effective working region becomes uniform, and the polishing rate becomes substantially constant.
[0041]
On the other hand, the rotation axis K1 of the polishing tool 8 is relative to the surface of the wafer W on the polishing surface 8a of the polishing tool 8 in the region 90 where the polishing tool 8 rides on the outer peripheral edge of the wafer W as shown in FIG. The height is inclined at an angle β in a direction in which the polishing tool 8 is higher than the height of the polishing surface 8a with respect to the surface of the wafer W in the region 91 where the polishing tool 8 escapes from the outer peripheral edge of the wafer W.
For this reason, the elastic deformation of the polishing surface 8a of the polishing tool 8 in the riding area 90 is reduced, and damage generated on the outer peripheral edge of the wafer W can be suppressed.
[0042]
Here, FIG. 10 shows a state in the riding area 90 and the escape area 91 of the polishing surface 8a of the polishing tool 8. As shown in FIG.
FIGS. 10A and 10B are views showing the state of the polishing surface 8a of the polishing tool 8, wherein FIG. 10A shows the state of the riding area 90, and FIG. 10B shows the state of the escape area 91. FIG. 10A and 10B are cross-sectional views of the regions 90 and 91 along the radial direction of the wafer W. FIG.
When the inclination angle β is relatively small, as shown in FIG. 10, elastic deformation occurs in the riding region 90 of the polishing surface 8 a of the polishing tool 8, but the elastic deformation amount is larger than the elastic deformation amount in the escape region 91. Relatively small. For this reason, in the run-up region 90 of the polishing surface 8a of the polishing tool 8, the contact pressure with respect to the outer peripheral end portion of the wafer W of the polishing surface 8a of the elastically deformed polishing tool 8 is reduced as compared with the case where the outer peripheral end of the wafer W is not inclined. Excessive polishing that occurs in the part can be suppressed.
Further, the processing energy that is no longer consumed by reducing the elastic deformation of the polishing surface 8a of the polishing tool 8 in the riding region 90 is relatively high in pressure that effectively acts on the surface to be polished of the wafer W described above. It concentrates on the high area | region PH and a polishing rate improves.
Further, the contact pressure of the polishing surface 8a of the polishing tool 8 that has been elastically deformed with respect to the outer peripheral end portion of the wafer W is reduced, so that the slurry SL attached to the polishing surface 8a of the rotating polishing tool 8 is polished in the riding region 90. It becomes easy to enter between the polishing surface 8 a of the tool 8 and the surface of the outer peripheral end of the wafer W. For this reason, the slurry is stably and efficiently supplied to the effective working region between the polishing surface 8a and the surface to be polished of the wafer W, and the polishing rate is improved and stabilized.
[0043]
On the other hand, in the relief area 91 of the polishing surface 8a of the polishing tool 8, it is considered that the applied pressure increases and the amount of elastic deformation increases in accordance with the reduction of the elastic deformation of the polishing surface 8a in the riding area 90. When the amount of elastic deformation of the polishing surface 8a increases in the escape region 91, the influence on the outer peripheral end of the wafer W also increases. However, in the escape region 91, the elastically deformed polishing surface 8a may wrap around the outer peripheral end of the wafer W. The effect is sufficiently smaller than the effect in the riding area 90.
[0044]
FIG. 11 shows a state in which the inclination angle β is relatively larger than that shown in FIG.
When the inclination angle β is increased, the elastic deformation of the polishing surface 8a of the polishing tool 8 is completely eliminated in the riding region 90 as shown in FIG. It can be set as the state in which a clearance gap is formed between them.
In such a state, the processing energy is hardly consumed in the riding area 90, and the processing energy is concentrated in the area PH where the pressure that effectively acts on the surface to be polished of the wafer W is relatively high. Further, the polishing rate can be further improved. In addition, since a gap is formed between the polishing surface 8a and the surface of the wafer W, the slurry SL can easily enter between the polishing surface 8a and the surface to be polished of the wafer W, and the slurry can enter the effective working region. SL can be supplied more stably and efficiently.
[0045]
Increasing the inclination angle β is considered to increase the amount of elastic deformation of the polishing surface 8a in the relief region 91 as shown in FIG. As described above, in the escape region 91, the influence of the elastic deformation of the polishing surface 8a in the escape region 91 is negligible although the influence is relatively small because the elastically deformed polishing surface 8a does not wrap around the outer peripheral edge of the wafer W. If this is not possible, for example, the processing pressure F of the polishing tool 8 on the wafer W is adjusted (decreased) to reduce the amount of elastic deformation of the polishing surface 8a in the relief region 91. Thereby, the influence of the elastic deformation of the polishing surface 8a in the relief area 91 can be reduced. Even if the processing pressure F is reduced, the processing energy is concentrated in the region PH, so that the reduction in the polishing rate can be minimized.
[0046]
As shown in FIG. 9A, when the rotation axis K1 is inclined at an angle β, the entire crescent-shaped region PR escapes from the outer peripheral edge of the wafer W on the polishing surface 8a according to the inclination of the angle β. Shift toward region 91. The high-pressure region PH that is an effective working region also shifts toward the region 91 that escapes from the outer peripheral edge of the wafer W on the polishing surface 8a. Therefore, the high-pressure region PH, which is an effective working region, does not have a symmetrical shape with respect to the X axis passing through the center of the wafer W, and is further away from the X axis passing through the center of the wafer W as the angle β increases.
Therefore, if the inclination angle β of the rotation axis K1 of the polishing tool 8 is set too large, the high pressure region PH, which is an effective working region, is completely separated from the X axis passing through the rotation center of the wafer W, and the polishing tool. When both the wafer 8 and the wafer W are rotated and the wafer W is polished, the central region of the wafer W cannot be sufficiently polished.
In order to prevent this, it is preferable to set the inclination angle β of the rotation axis K1 of the polishing tool 8 to be smaller than the inclination angle α, and the high-pressure region PH which is an effective working region is the rotation of the wafer W. It is preferable to set the inclination angle β so as to intersect the X axis passing through the center.
[0047]
As described above, the polishing process by the polishing tool 8 is performed along the traveling direction D while the excessive polishing of the outer peripheral end portion of the wafer W is suppressed, and the outer peripheral end portion of the polishing tool 8 is formed on the wafer W shown in FIG. The processing end point P2 is reached.
When the outer peripheral edge of the polishing tool 8 moves to the processing end point P2 of the wafer W, the processing of the surface to be polished of the wafer W is ended. The polishing process is ended by raising the polishing tool 8 in the Z-axis direction.
As described above, when the polishing process is finished at a position where the outer peripheral end portion of the wafer W and the polishing tool 8 substantially overlap, the outer peripheral end portion of the wafer W is hardly damaged.
Even if the processing is finished at a position where the outer peripheral end of the polishing tool 8 slightly protrudes from the processing end point P2, the outer diameter of the polishing tool 8 and the diameter of the wafer W are substantially equal. There is almost no velocity component toward the center of the wafer W of 8a, and damage to the outer peripheral edge of the wafer W due to the rising of the polishing surface 8a hardly occurs.
[0048]
As described above, according to the polishing method according to the present embodiment, the elasticity in the run-up region 90 on the outer peripheral end of the wafer W generated on the polishing surface 8a of the polishing tool 8 that rotates the rotation axis K1 of the polishing tool 8. By inclining in a direction to reduce the deformation, the elastic deformation of the polishing surface 8a of the polishing tool 8 is relieved, and accordingly, a high pressure region PH that is an effective working region between the wafer W and the polishing surface 8a. The processing pressure increases.
As a result, the processing energy is concentrated in the effective working region between the wafer W and the polishing surface 8a, and the polishing efficiency is improved.
Further, according to the present embodiment, since the height of the run-up area 90 of the polishing surface 8a of the polishing tool 8 on the outer peripheral end of the wafer W is relatively high, a gap is formed between them, and polishing is performed. Slurry easily enters between the surface 8a and the surface to be polished of the wafer W. That is, the slurry adhering to the rotated polishing surface 8a is carried between the polishing surface 8a and the surface to be polished of the wafer W.
As a result, the slurry is stably and efficiently supplied to the effective working area between the polishing surface 8a and the surface to be polished of the wafer W, and the polishing rate is improved and stabilized.
[0049]
Furthermore, in this embodiment, since the consumption of the processing energy due to running on the outer peripheral edge of the wafer W can be suppressed, the pressure of a part of the polishing surface 8a of the polishing tool 8, that is, the crescent-shaped region PR described above is high. When the surface to be polished of the wafer W is partially polished by the region PH, the processing energy is concentrated on the region PH which is an effective working region that is narrowed, so that the warp existing on the surface of the wafer W in the region PH. The followability to the swell improves.
That is, on the surface to be polished of the wafer W, distortion or the like generated up to the previous process affects the shape of the wafer W, and there may be warping or waviness of about several μm to 10 μm. When 8a strongly presses the outer peripheral edge of the wafer W, the followability to warpage and undulation of the region PH where the pressure of the crescent-shaped region PR, which is an effective working region for polishing, is high is reduced. In the form, this decrease in followability can be prevented, and the processing uniformity can be improved.
[0050]
Further, according to the present embodiment, the elastic deformation of the polishing surface 8a in the region 90 where the polishing surface 8a of the polishing tool 8 rides on the outer peripheral edge of the wafer W is reduced, so that the polishing surface 8a of the polishing tool 8 can be reduced. There is little deterioration in quality, and the frequency of conditioning of the polishing surface 8a can be suppressed.
[0051]
As described above, by tilting the rotation axis K1 at a large tilt angle β, the region PH in which the pressure of the crescent-shaped region PR, which is an effective working region, is high, passes through the center of the wafer W in the X-axis direction. If the center region of the wafer W cannot be sufficiently polished by being separated from the straight line, for example, instead of the X-axis table 52 holding the rotary table 41, the rotary table 41 in the X-axis and Y-axis directions is used. By holding the rotary table 41 on the XY table that holds the slidable and moving the rotary table 41 to the X axis and the Y axis, the pressure in the crescent-shaped region PR, which is an effective working region, is high. The region PH may pass over the rotation center of the wafer W.
[0052]
Second embodiment
Next, another polishing method using the above polishing apparatus 1 will be described as a second embodiment of the present invention.
12A and 12B are diagrams for explaining a polishing method according to the second embodiment of the present invention, in which FIG. 12A is a diagram illustrating an inclined state of the polishing tool 8 in the polishing apparatus 1, and FIG. It is a figure which shows the positional relationship of the relative movement direction of the wafer W and the grinding | polishing tool 8. FIG.
In the present embodiment, the polishing tool 8 and the wafer W are relatively moved in a positional relationship as shown in FIG. That is, the polishing tool 8 is moved in the direction of travel D along a straight line X2 parallel to the straight line X1 passing through the rotation center of the wafer W along the X-axis direction and separated by a predetermined distance d.
Further, as shown in FIG. 12A, the holding surface of the rotary table 41 is set so that the rotation axis K1 of the polishing tool 8 is along the Y-Z plane perpendicular to the traveling direction D of the polishing tool 8 relative to the wafer W. Inclined at an angle β from an axis O perpendicular to 41a. The rotation axis K1 of the polishing tool 8 is inclined at an angle β along the YZ plane with respect to the axis O perpendicular to the holding surface 41a of the rotary table 41.
Further, as shown in FIG. 12A, the inclination direction of the angle β is relatively low with respect to the wafer W of the polishing surface 8a of the polishing tool 8 positioned on a straight line passing through the center of the wafer W. The direction.
[0053]
The inclination angle β of the rotation axis K1 of the polishing tool 8 is such that the height difference Hβ in the Z-axis direction at the front and rear ends of the polishing surface 8a of the polishing tool 8 shown in FIG. Set to a value of degree. That is, the inclination angle is about 15 to 30 μm with respect to the length of 8 inches.
[0054]
When the rotation axis K1 of the polishing tool 8 is inclined at an angle β, the effective action area S of the polishing surface 8a of the polishing tool 8 with respect to the wafer W becomes, for example, a crescent shape as shown in FIG. .
The distance d between the straight lines X1 and X2 is set such that the effective action area S of the polishing surface 8a shown in FIG. 12B is located on the straight line X1 passing through the center of the wafer W.
Furthermore, the rotation direction R1 of the polishing tool 8 and the rotation direction R2 of the wafer W are opposite to each other as shown in FIG.
[0055]
FIG. 13 is a diagram for explaining a polishing procedure of the polishing method according to the present embodiment.
For example, the polishing process of the wafer W is started from a processing start position P1 shown in FIG.
That is, the polishing tool 8 is pressed against the wafer W so that the effective working area S of the polishing surface 8a of the polishing tool 8 is positioned at the processing start position P1 of the wafer W.
At this time, the region shown in the circle A is a run-up region where the polishing surface 8a of the polishing tool 8 rides on the outer peripheral end of the wafer W, and the region shown in the circle B is the polishing surface 8a of the polishing tool 8 on the outer peripheral end of the wafer W. It becomes an escape area to escape from the part.
In this riding region, since the rotation axis K1 of the polishing tool 8 is inclined at an angle β, the elastic deformation of the polishing surface 8a is reduced, and damage to the outer peripheral end of the wafer W is suppressed.
[0056]
When the polishing tool 8 is moved in the relative advancing direction D from the position shown in FIG. 13A, the effective action area S moves along the radial direction of the rotating wafer W. For this reason, as shown in FIG. 13B, the effective working region S passes through the rotation center of the wafer W, so that insufficient polishing at the center of the wafer W does not occur.
[0057]
As the polishing tool 8 is moved in the relative traveling direction D, the riding area shown in the circle A approaches the straight line X1. For this reason, the distance between the polishing surface 8a in the riding region and the surface to be polished of the wafer W approaches, and elastic deformation of the polishing surface 8a in the riding region occurs. Alternatively, the amount of elastic deformation that has been reduced increases.
For this reason, as shown in FIG. 13C, the polishing is finished when the front end portion in the traveling direction D of the effective working region S reaches the processing end position P <b> 2 of the outer peripheral end portion of the wafer W.
Thereby, excessive polishing of the outer peripheral end portion of the wafer W due to the rising of the polishing surface 8a can be prevented.
[0058]
As described above, according to the present embodiment, even when the rotation axis K1 is inclined in only one direction by appropriately selecting the arrangement and relative movement direction of the wafer W and the polishing tool, the outer peripheral end of the wafer W It is possible to prevent excessive polishing of the portion and avoid occurrence of insufficient polishing at the center of the wafer W.
[0059]
Third embodiment
Next, another polishing method using the above polishing apparatus will be described as a third embodiment of the present invention.
In the first embodiment described above, the rotation axis K1 of the polishing tool 8 is inclined at an inclination angle α toward the traveling direction of the polishing tool 8 with respect to a direction perpendicular to a plane parallel to the holding surface 41a of the rotary table 41. And the elasticity of the polishing surface 8a in the region where the polishing surface 8a rides on the outer peripheral end of the surface to be polished of the wafer W with respect to the direction perpendicular to the holding surface 41a of the rotary table. Polishing was performed at an inclination angle β in a direction to reduce deformation.
In the present embodiment, as in the first embodiment described above, polishing is performed by inclining in two different directions at inclination angles α and β, but the correction surface of the correction tool parallel to the holding surface 41a of the holding table 41 is further provided. A polishing tool 8 having a polishing surface 8a that is faced along the surface is used.
Specifically, as shown in FIGS. 14A and 14B, the polishing tool 8 has a rotation axis K1 with respect to an axis O perpendicular to a plane parallel to the holding surface 41a of the holding table 41. It is inclined at an inclination angle α toward the traveling direction D of the polishing tool, and is inclined at an inclination angle β along a plane perpendicular to the traveling direction D with respect to the axis O.
Further, the polishing surface 8a of the polishing tool 8 is inclined at an angle γ synthesized from the angle α and the angle β.
[0060]
For example, as shown in FIG. 15A, the method of forming the polishing surface 8a of the polishing tool 8 as described above is such that the rotation axis K1 of the polishing tool 8 is inclined at an angle α toward the traveling direction D of the polishing tool 8. Further, although not shown in the drawing, the rotation is performed in a state inclined at an inclination angle β along a plane perpendicular to the traveling direction D with respect to the axis O.
Further, as shown in FIG. 15B, the correction tool 56 is installed on the X-axis table 52. The correction tool 56 has a correction surface 56a perpendicular to the axis O, that is, perpendicular to the rotation axis K1 that is not inclined, and the correction surface 56a is formed on the holding surface 41a of the holding table 41 that holds the wafer W. Parallel planes. For example, abrasive grains such as diamond abrasive grains are fixed to the correction surface 56a.
15C, the X-axis table 52 is moved relative to the polishing tool 8 so that the rotation axis K1 of the polishing surface 8a passes through the correction surface 56a of the correction tool 56. Then, the tip of the correction tool 56 is brought into contact with the polishing surface 8a to form the polishing surface 8a by chamfering (facing processing).
The polishing surface 8a formed by such facing processing is a conical surface, and the inclination angle of the generatrix of the conical surface is an angle γ obtained by combining the angle α and the angle β as shown in FIG. An inclined polished surface 8a is obtained.
[0061]
When the polishing surface 8 a of the polishing tool 8 inclined at the angle γ is pressed against the wafer W, the polishing surface 8 a contacts the surface of the wafer W substantially in parallel. Moreover, the shape of the effective action area S between the wafer W and the polishing surface 8a is, for example, a linear shape extending in the radial direction of the polishing tool 8, as shown in FIG. Further, the shape of the action region S changes according to the processing pressure of the polishing tool 8 on the wafer W, and when the processing pressure increases, the shape changes from a linear shape to a fan shape.
Further, the position of the action region S is inclined at an inclination angle β in the direction in which the rotation axis K1 of the polishing tool 8 reduces elastic deformation, and therefore the X-axis direction passing through the center of the wafer W according to the inclination angle β. Is slightly shifted from the straight line to the relief region 91 side from the outer peripheral end of the wafer W on the polishing surface 8a of the polishing tool 8.
[0062]
At this time, the polishing surface 8a of the polishing tool 8 is formed in a curved surface in the region 90 of the polishing tool 8 that runs on the outer peripheral end of the wafer W and the escape region 91 from the outer peripheral end of the wafer W. The height of the polishing surface 8a of the polishing tool 8 relative to the surface of W is higher than the height of the polishing surface 8a of the polishing tool 8 relative to the surface of the wafer W in the action region S.
For this reason, even if the polishing tool 8 is pressed against the wafer W, the elastic deformation amount of the polishing surface 8a of the polishing tool 8 in the riding area 90 is larger than that in the above-described embodiment, that is, the polishing surface 8a is flat. Get smaller.
[0063]
Therefore, since the elastic deformation amount of the polishing surface 8a of the polishing tool 8 is small, the inclination angle β in the direction of reducing the elastic deformation of the rotation axis K1 of the polishing tool 8 can be reduced.
As a result, the amount by which the position of the action region S shifts from the straight line in the X-axis direction passing through the center of the wafer W toward the escape region 91 from the outer peripheral end of the wafer W on the polishing surface 8a of the polishing tool 8 can be suppressed as much as possible. For this reason, due to the relative movement of the wafer W and the polishing tool 8 in the X-axis direction, the action region S advances in the radial direction of the rotating wafer W and passes through the rotation center of the wafer W. The occurrence of insufficient polishing at the center can be prevented.
[0064]
Further, according to the present embodiment, the polishing surface 8a of the polishing tool 8 is inclined at an angle γ by combining the angle α and the angle β, so that the polishing surface 8a of the polishing tool 8 and the surface to be polished of the wafer W are separated. Since the effective working area S is further narrowed and the shape of the working area S is formed by the shape of the polishing surface 8a of the polishing tool 8, there is little variation in the area of the working area S, and the polishing rate is further increased. It becomes easy to stabilize, and the followability to the warp and the undulation existing on the surface of the wafer W in the action region S is further improved, so that the processing uniformity of the polished surface of the wafer W can be improved.
[0065]
The present invention is not limited to the various embodiments described above.
In the above-described embodiment, the entire surface to be polished of the wafer W in the state where the rotation axis K1 of the polishing tool 8 is inclined in two different directions at the inclination angles α and β by the rotation axis inclination mechanism 61 of the polishing apparatus 1, respectively. The case of performing the above processing has been described.
In the above-described embodiment, since the rotation axis K1 of the polishing tool 8 is inclined at the inclination angle α toward the traveling direction D of the polishing tool 8, when the polishing tool 8 is moved relative to the wafer W to a certain position. The elastic deformation due to running on the outer peripheral end of the wafer W of the polishing surface 8a does not occur or becomes a very small value. Note that the position of the polishing tool 8 with respect to the wafer W varies depending on the inclination angle α, the processing pressure of the polishing tool 8 on the wafer W, and the inclination angle of the polishing surface 8a.
[0066]
For this reason, when the polishing tool 8 is moved relative to the wafer W to a position where the polishing surface 8a does not undergo elastic deformation due to running on the outer peripheral edge of the wafer W or reaches a very small value, the polishing tool 8 It is good also as a structure which returns the rotating shaft K1 to the direction perpendicular | vertical to the holding surface 41a of the turntable 41 regarding the direction which reduces elastic deformation.
In this way, the polishing surface 8a of the polishing tool 8 that moves by the relative movement of the polishing tool 8 and the wafer W in the X-axis direction is eliminated by eliminating the inclination of the rotation axis K1 of the polishing tool 8 in a direction that reduces elastic deformation. Since the effective action area between the surface of the wafer W and the surface to be polished moves along the straight line in the X-axis direction passing through the rotation center of the wafer, insufficient polishing of the central portion of the wafer W does not occur.
[0067]
In the middle of the relative movement of the polishing tool 8 and the wafer W in the X-axis direction, the rotational axis K1 of the polishing tool 8 is returned to the direction perpendicular to the holding surface 41a of the rotary table 41 with respect to the direction of reducing elastic deformation. The relative position of each of the two tilt adjustment blocks 62 and 63 of the rotating shaft tilt mechanism 61 of the polishing apparatus 1 is not manually adjusted, for example, by a servo motor or a cylinder device. When the relative position in the X-axis direction reaches a predetermined position, it can be configured to drive.
[0068]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the excessive grinding | polishing of the outer peripheral edge part of a grinding | polishing target object by the elastic deformation in the riding area to the outer peripheral edge part of the grinding | polishing target object of a grinding | polishing tool can be suppressed.
Furthermore, by tilting the polishing surface of the polishing tool in two different directions, the effective working area can be narrowed, and the supply of the abrasive between the polishing surface and the surface to be polished can be stabilized. Processing uniformity within the polished surface can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a polishing apparatus according to an embodiment of the present invention.
FIG. 2 is a view for explaining a rotating shaft tilting mechanism as the rotating shaft tilting means of the present invention.
3 is a cross-sectional view showing a structure of a rotating shaft tilt mechanism 61. FIG.
4 is a view showing a structure of an angle adjustment block 62. FIG.
5 is a view showing a structure of an angle adjusting block 63. FIG.
FIG. 6 is a view for explaining the polishing method of the present invention, and is a view showing the inclination in the traveling direction of the rotation axis K1 of the polishing tool.
FIG. 7 is a diagram for explaining a polishing method of the present invention, and is a diagram showing an inclination in a direction to reduce elastic deformation of a polishing surface in a riding area of a rotation axis K1 of a polishing tool.
FIG. 8 is a diagram for explaining a polishing method of the present invention, and is a diagram showing a relative positional relationship between a wafer W and a polishing tool 8;
9A is a diagram showing an example of a pressure distribution generated between the polishing surface 8a of the polishing tool 8 and the surface to be polished of the wafer W, and FIG. 9B is an AA line in FIG. 9A. It is sectional drawing of a direction.
10A and 10B are views showing the state of the polishing surface 8a of the polishing tool 8, wherein FIG. 10A is a cross-sectional view showing the state of the riding area 90 and FIG.
11 is a diagram showing a state of the polishing surface 8a of the polishing tool 8 when the inclination angle β is relatively larger than that shown in FIG.
FIG. 12 is a diagram for explaining a polishing method according to a second embodiment of the present invention.
FIG. 13 is a view for explaining a polishing procedure of a polishing method according to a second embodiment of the present invention.
FIG. 14 is a view for explaining a polishing method according to a third embodiment of the present invention.
FIG. 15 is a diagram for explaining a facing method of a polishing surface of a polishing tool.
FIG. 16 is a diagram showing the shape of an effective action area S between the wafer W and the polishing surface 8a.
FIG. 17 is a perspective view showing an example of a conventional polishing apparatus.
FIG. 18 is a diagram for explaining an example of a conventional polishing method.
19 is a diagram showing an example of a pressure distribution generated between a wafer and a polishing tool in the polishing method shown in FIG.
FIG. 20 is a cross-sectional view showing elastic deformation at the outer peripheral edge of the wafer caused by pressing the polishing surface of the polishing tool against the wafer.
FIG. 21 is a plan view showing a state of excessive polishing of the outer peripheral edge of the wafer W caused by elastic deformation of the polishing surface of the polishing tool.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Polishing apparatus, 3 ... Column, 8 ... Polishing tool, 8a ... Polishing surface, 11 ... Z-axis moving mechanism, 20 ... Spindle holder, 21 ... Spindle spindle, 41 ... Rotary table, 51 ... X-axis moving mechanism, W ... Wafer.

Claims (15)

A polishing table made of an elastic body , which is held by a rotating member and has a polishing surface along a plane orthogonal to the rotation axis of the rotating member, is rotated according to the rotation of the rotating member, and the polishing surface of the polishing tool is held by a holding table. pressed relatively at a predetermined processing pressure to the surface to be polished of the object to be polished that is held by the upper, relative along a plane parallel with said polishing tool and the object to be polished on the holding surface of the holding table wherein a polishing method for polishing the surface of the object to be polished is moved,
It said polishing tool is first towards the traveling direction of the relative movement direction between the holding table and the grinding tool rotation shaft of the stationary the rotating member with respect to the direction perpendicular to the holding surface of the holding table by an angle tilted, and,
Wherein as the polishing surface of the polishing tool to reduce the elastic deformation of the polishing surface of the elastic member, wherein provided in the abrasive tool in the region runs onto the outer peripheral edge of the surface to be polished of the object to be polished, of the rotary member A rotation axis with respect to the surface to be polished of the object to be polished in a region where the polishing surface of the polishing tool rides on an outer peripheral end of the surface to be polished of the polishing tool along a plane perpendicular to the traveling direction. height, a second angle becomes higher orientation than the height to the surface to be polished of the object to be polished in the region to escape from the outer circumferential edge of the surface to be polished of the polishing surface wherein the object to be polished of the polishing tool Just tilt ,
The surface to be polished of the object to be polished is polished by the polishing surface of the polishing tool.
Polishing method. Using a polishing tool having a diameter substantially equal to the diameter of the surface to be polished of the object to be polished as the polishing tool ,
Positioning the outer peripheral end of the polishing surface of the polishing tool located outside the surface to be polished of the object to be polished at the outer peripheral end of the surface to be polished of the object to be polished;
Wherein the polishing tool with the polishing surface relatively moved in the direction area overlapping with the surface to be polished increases polished the surface to be polished,
The polishing process is stopped at the position where the outer peripheral end of the polishing surface of the polishing tool reaches the outer peripheral end of the surface to be polished of the object to be polished.
The polishing method according to claim 1. The polishing method according to claim 1 for polishing using a polishing tool having an annular grinding surface as the grinding tool. Modification of the angular rotation shaft of the first rotary member and the second angle in the polishing parallel correction tool to the holding surface of the holding table tool which rotates in response to rotation of the front rotary member inclined state using a polishing tool having a facing machined polished surface by moving the relative along the surface,
The polishing method according to claim 3. Larger than the first angle and the second angle,
The polishing method according to claim 1. Rotating the holding table, perform the polishing while rotating the polishing target object,
The polishing method according to claim 1. Performing the polishing by the direction of rotation of the polishing tool and the object to be polished in the opposite direction,
The polishing method according to claim 6. The polishing method according to claim 1, wherein the polishing is performed with an abrasive interposed between a polishing surface of the polishing tool and a surface to be polished of the object to be polished. Positioning the outer peripheral end of the polishing surface of the polishing tool located outside the surface to be polished of the object to be polished at the outer peripheral end of the surface to be polished of the object to be polished;
When said area of overlapping with the surface to be polished of the object to be polished and the polishing surface of the polishing tool to polish is moved in the direction of increasing, at least the surface to be polished of the polishing target of the polishing surface of the polishing tool Inclining by the second angle to a position where elastic deformation of the polishing surface due to riding on the outer peripheral end portion does not occur,
The polishing method according to claim 1. Wherein After the polishing tool to the position where elastic deformation is not generated in the polished surface by riding up on the outer peripheral edge of the surface to be polished of the polishing surface of the polishing tool reaches said rotary member rotating shaft before Symbol the holding table Perpendicular to the holding surface,
The polishing method according to claim 9. A rotating member;
A holding table for holding an object to be polished;
A polishing tool comprising an elastic polishing surface along a plane that is held by the rotating member and orthogonal to the rotation axis of the rotating member ;
Vertical axis moving means for moving the rotating member up and down in the vertical direction to separate or press the polishing surface of the polishing tool against the surface to be polished held by the holding table;
Moving the holding table relative to the polishing tool in the horizontal direction, and contacting or separating the polished surface of the object to be polished held by the holding table and the polishing surface of the polishing tool; Horizontal movement means;
A rotating shaft tilting means provided at at least three locations on the outer periphery of the rotating member and tilting the rotating shaft of the rotating member in two directions orthogonal to each other in the horizontal direction ;
Have
Adjusting the rotating shaft tilting means provided in at least three places on the outer periphery of the rotating member;
Towards the traveling direction when approximating the said holding table and the polishing tool by said horizontal moving means, a first angle of the rotation axis of the rotating member with respect to the direction perpendicular to the holding surface of the holding table Just tilt and
The polishing tool is provided in a region where the polishing surface of the polishing tool , which is moved by the operation of the vertical axis direction moving means and the horizontal direction moving means , rides on the outer peripheral end of the surface to be polished of the object to be polished. In order to reduce the elastic deformation of the polished surface of the elastic body, the polishing tool is applied to the outer peripheral end of the polished surface of the object to be polished in a direction orthogonal to the traveling direction of the rotation axis of the rotating member . second angle that the height relative to the surface to be polished in the area riding of the polishing surface, higher than the height relative to the surface to be polished in the region where the polishing surface of the polishing tool to escape from the outer peripheral edge of the surface to be polished Just tilt and
With the rotating shaft of the rotating member inclined by the first angle and the second angle, the polishing tool is pressed against the object to be polished by the vertical axis direction moving means to apply a processing pressure to the object to be polished. While being added to the object, the polishing surface of the object to be polished and the polishing surface of the polishing tool are brought into rotational contact according to the rotation of the rotating member, and the object to be polished is polished by the horizontal movement means. Polishing the surface to be polished of the object to be polished by relatively moving the surface and the polishing surface of the polishing tool,
Polishing equipment. The polishing tool has an annular polishing surface;
The polishing apparatus according to claim 11. The polishing surface of the polishing tool is facing the processing by the rotation axis of the rotating member is relatively moved along the balancing plane parallel correction tool the abrasive tool which rotates in an inclined state wherein in each direction on the holding table Being
The polishing apparatus according to claim 12 . The polishing apparatus further includes a rotating unit that rotates the holding table.
The polishing apparatus according to claim 11. The polishing apparatus further includes an abrasive supply means for supplying an abrasive interposed between the polishing surface and the surface to be polished.
The polishing apparatus according to claim 11.

Images